There is already a known process for die-stamping blanks using a stamp/die assembly. Using such prior art processes, blanks to be die-stamped is extracted successively from blank supply means, such as a magazine; the blank is transferred between the stamp and the die spaced apart; the stamp and the die are brought closer, until they contact either side of the blank to die-stamp it; if appropriate, matching or mutually adjacent parts of the blank are fastened together, by adhesive bonding; the stamp and the die are moved apart; and the blank is extracted and discharged.
A blank die-stamping device which can be used on a packaging machine, such as a tray-making machine, is likewise known and comprises a stamp and a die interacting with one another, means for bringing the stamp and the die closer and for spacing them apart between two end positions. These positions include an inactive position, in which they are spaced apart, and an actual die-stamping position, in which they are fitted one in the other, and means for extracting and for discharging the die-stamped blanks.
Reference can be made, for example, to the document FR 2,248,932.
This die-stamping process and device are intended for a packaging machine possessing means for supplying blanks, means for extracting a blank from these supply means, means for transferring this blank to the die-stamping device, means for extracting the die-stamped blank from the die-stamping device and for discharging it towards another station for filling it with contents to be packaged.
Such prior art die-stamping processes and device are usually designed to operate with a single format of blanks. The blanks are generally made of cardboard, having folding lines and matching or mutually adjacent parts intended to be fastened together by adhesive bonding (tabs, flaps, etc). In fact, the best known packaging machines associated with such die-stamping devices generally operate under a single blank format. Achieving a change in blank format is therefore either impossible or is carried out by changing the stamp and the die completely or manually, this being lengthy, difficult, inaccurate, costly, etc.
The document U.S. Pat. No. 3,218,940 describes a cardboard-shaping machine which possesses such a die-stamping device adjustable manually so as to be adapted to cardboard blanks of different formats. For this purpose, the stamp and the die are each made of several plural shiftable, but lockable relative in the two longitudinal and transverse directions, the means for guiding and driving these parts ensuring these shifts and locks. However, these shifts and locks are manual and, moreover, separate and distinct for the stamp and the die, thus making it impossible, in practice, to carry out numerous rapid, easy and reproducible adjustments.
Other devices are also known from the documents U.S. Pat. No. 2,641,973, U.S. Pat. No. 2,798,416, DE 292,080, U.S. Pat. No. 3,046,849, U.S. Pat. No. 1,386,292, U.S. Pat. No. 4,033,242 and U.S. Pat. No. 3,357,700.
In the general sector of packaging, it is also known that there is the possibility of adjusting the members of a machine, depending on the conditions of use, including the dimensions of the processed packages (see the documents FR 2,029,300 and EP 0,142,007). However, such adjustments are not, suitable for the die-stamping of blanks.
The first object of the present invention is, therefore, to provide a method and apparatus for programmable automatic control of die and stamp size in a die-stamping assembly, each die-stamping member of which is in several adjustable and lockable parts. More specifically, the object of the invention is to ensure automatic, rapid, accurate and reproducible adjustment. The second main object of the invention is to carry out such an adjustment in machinery adapted for use in packaging is concerned.
For this purpose, the invention provides a process for the dimensional adjustment of a die-stamping assembly comprising two die-stamping members, a stamp and a die, each composed of several plural parts having relative positions adjustable and lockable as a result of lateral position changes, the two die-stamping members being moveable after axial engaging/disengaging shifts. The two die-stamping members being each separately, either locked or unlocked and, together, either engaged or disengaged to adapt the die-stamping assembly dimensionally to a blank format to be die-stamped and bring it into a stand-by position, from which the die-stamping of the blank is made possible after the subsequent interaction of the two die-stamping members, this stand-by position being such that the two die-stamping members are disengaged, locked and with lateral die-stamping spacings between their corresponding component parts adapted to the thickness of the blank, wherein the two die-stamping members are first unlocked, the appropriate transverse position changes are subsequently executed, and finally the two die-stamping members are locked, said process being defined in that the following steps are carried out: in a zero calibration step, the two die-stamping members are first brought from their disengaged state into their engaged and unlocked state, with their corresponding component parts in contact, after configurational and engaging/disengaging shifts, and in a predetermined reference configuration; subsequently, in an initial adjustment step, action is taken on only one of the two die-stamping members, the driving adjustment member, ensure its position change, the driving adjustment member in turn acting directly on the other die-stamping member, the driven adjustment member, to ensure its position change in synchronism, until a first die-stamping member has been adjusted dimensionally; and thereafter, the first die-stamping member is locked; in a second adjustment step, action is taken on only the second die-stamping member, to ensure its position change in the direction of a lateral spacing apart from the first die-stamping member, until the lateral die-stamping spacings are reached, the second die-stamping member then being adjusted dimensionally; the second die-stamping member is locked; and an engaging/disengaging shift of the two die-stamping members is executed to bring them into the stand-by position, the effect of this being to ensure automatic, rapid, accurate and reproducible adjustment of the die-stamping assembly.
The invention subsequently provides a blank die-stamping assembly comprising two die-stamping members, a stamp and a die, each in several plural having relative positions adjustable and lockable after lateral position changes by lateral driving and locking means, the two die-stamping members being moveable relative after axial engaging/disengaging shifts by axial driving and locking means, the two die-stamping members being movable, each separately, either locked or unlocked and, together, either engaged or disengaged, to dimensionally adjust the die-stamping assembly which, can be in a stand-by position, in which the die-stamping members are disengaged, locked and with a preset space between their corresponding component parts, and in a die-stamping position, in which the die-stamping members are engaged and interact for the effective die-stamping of a blank placed between them, wherein the lateral means for driving and locking the two die-stamping members are shared by the two die-stamping members and comprise, positive two-way drive means lockable in any position, coupled to and acting directly on one of the two die-stamping members, the driving member, and, single-direction actuator lockable in any position, coupled to and acting directly on the other die-stamping member, the driven member, such that, when the single-direction actuators are unlocked, these means act on the driven member so as to urge it into contact with the driving member, the two die-stamping members being engaged, and in the second place the two-way drive means drive the driven member indirectly via the driving member.
Finally, the invention provides, a process for the die-stamping of blanks and, a die-stamping machine putting into practice this adjustment process and this die-stamping assembly, which are intended for packaging.
One of the technical arrangements ensuring that the adjustment of the die-stamping assembly is automatic, rapid, accurate and reproducible is the use of adjustment means which are mechanized and can therefore be controlled and which act directly only on one of the two die-stamping members to shift it, the so-called driving member, the latter in turn ensuring the shift for the other die-stamping member, the so-called driven member. For this purpose, single acting jacks act on the driven member to urge it into contact with the driving member. Also, adjustment is carried out when the two die-stamping members are engaged one in the other. Preferably, the driving member is the die which can thus surround the stamp subjected elastically to compressed-air jacks in the direction of expansion. Threaded drive rods ensure the lateral position changes of the die and allow the position of the latter to be marked. To make it possible to ensure reproducibility, there is preferably an initial step involving the zero calibration of the two die-stamping members at a zero point corresponding to an extreme, minimum format.